Amazon's Chattanooga and Charleston, Tenn., distribution centers are powering up their workforces as the nation's No. 1 online retailer hires 70,000 seasonal employees nationally, up 40 percent from last Christmas.

Thousands more workers are expected to be hired at Amazon's Chattanooga center, and hiring will ramp up at its Bradley County facility, as well, the company said Tuesday.

Kelly Cheeseman, a spokeswoman for Seattle-based Amazon, declined to be specific about numbers, but she put the hiring at the company's five fulfillment centers in Tennessee at "thousands and thousands" of workers.

Interested candidates can apply at www.amazonfulfillmentcareers.com, she said.

Doug Berry, the Cleveland-Bradley County Chamber of Commerce's vice president of economic development, said Amazon already has nearly tripled its full-time workforce in Charleston over what it promised in 2010 to about 800.

"That's a much greater commitment," he said. Berry added that seasonal hiring already has begun in the northern Bradley County facility.

The Chattanooga facility and the Charleston site were estimated to have had about 5,000 full-time and temporary jobs last Christmas season.

According to Amazon, seasonal employees earn on average 94 percent of starting wages of its warehouse workers and are eligible for health care benefits. Many temporary seasonal jobs lead to long-term positions, the company said.

"So far this year, we have converted more than 7,000 temporary employees in the U.S. into full-time, regular roles and we're looking forward to converting thousands more after this holiday season," said Dave Clark, Amazon's vice president of worldwide operations and customer service, in a statement.

Berry said Amazon uses several temporary employment agencies in the region.

"We're very excited and happy to have the company and its sister facility," he said. Berry said Amazon already has built out its mezzanine in Charleston, much as it did at its Chattanooga location.

The seasonal hiring numbers don't include customer-service jobs, which also will increase through the end of the year, according to the Internet retailer.

Amazon had 97,000 full-time and part-time employees as of the end of June. In July, the company said it had 20,000 full-time workers at its warehouses.

The seasonal hiring already has begun as it staffs up to handle the crush of goods coming into its warehouses to meet shopper demand, the company said. Amazon plans to hire another wave of seasonal workers closer to the holidays to ship those products off to customers.

This summer in Chattanooga, before a visit by President Barack Obama to the Enterprise South industrial park facility, the company said it employed about 1,800 full-time and 700 part-time workers at that site. Then, Amazon said it was adding dozens of full-time jobs in Chattanooga and Charleston.